So I'm getting ready for my first GT with Deathwatch in about a month, and I thought I was pretty set on my list until the Armoured Speartip detachment dropped. Deathwatch seem to be pretty good at punching up but I'm not sure how well the army can handle multiple T12 vehicles with the standard kill team spam lists.
Off the top of my head I figured both Indom teams with lethal hits from Mission Tactics + Kraken rounds and Veterans with their dev wound thunder hammers would be the best options. However, after running some quick math it looks like the Indom team only takes about 8 wounds off a Land Raider Redeemer on average and the Vets would be lucky to get 4-5. Plus, that's assuming the squad doesn't get ravaged by overwatch beforehand, and in the case of the Indom team, that the LR doesn't pop smoke.
I don't think the detachment has been out long enough to see what sort of lists most people will be running with it, but there might be other ways to deal with it outside of popping all their big transports. Maybe just S2S around and picking off any smaller units they can use for secondaries would be enough to win the scoring game. I guess it might be hard to say until we see what the "meta" Speartip list looks like.